1. Field of the Invention
The present invention relates to a steering assist apparatus provided to a vehicle such as a car and configured to recognize an environment ahead of the vehicle and apply steering force to a steering mechanism of the vehicle. More specifically, the present invention relates to a steering assist apparatus capable of reducing an interference with driver's steering operations when avoiding a neighboring vehicle.
2. Description of the Related Art
A steering assist apparatus is, for example, to recognize an environment ahead of a vehicle using a stereo camera and the like, and apply steering force to a steering mechanism of the vehicle to assist driver's driving operations.
When the vehicle has a deviation tendency from a traveling lane, for example, the steering assist apparatus executes a lane deviation prevent control for applying steering force in a deviation preventing direction, or a lane-keeping assist control for applying steering force so that the vehicle travels along a target traveling position set within the lane.
When there is an obstruction such as a preceding vehicle in a lane next to a lane where the vehicle is traveling and the vehicle passes to travel ahead of the obstruction, for example, a driver of the vehicle tend to avoid the obstruction by traveling a position deflected from the center of the lane or intentionally traveling out of the lane in order to keep a distance between the vehicle and the obstruction.
JP-A-2001-048036 discloses a traveling line follow-up apparatus of the vehicle, which dislocates a target traveling line away from an obstruction to avoid the obstruction in case where there is an obstruction in a traveling lane next to a traveling lane in which the vehicle is traveling.
Further, JP-A-2006-069344 discloses a technology in which, when there is a traffic jam in a neighboring lane, a traveling position of a vehicle is dislocated in a direction away from the neighboring lane to deal with a neighboring vehicle which may move into the lane of the vehicle from the neighboring lane.
Further, JP-A-2000-025631 discloses a technology in which, an approach degree with respect to a preceding vehicle is detected based on an inter-vehicle distance detected by an inter-vehicle distance sensor such as a radar and steering force is reduced corresponding to the detected approach degree.
In the technologies disclosed in JP-A-2001-048036 and JP-A-2006-069344, however, the target traveling line is dislocated regardless of the lateral position of the vehicle in the lane when there is an obstruction in the neighboring lane or there is a traffic jam in the neighboring lane. With such configurations, for example, the target traveling line is changed even when the neighboring vehicle in the neighboring lane travels sufficiently away from a traveling lane of the vehicle so that a driver of the vehicle does not feel a need to avoid the neighboring vehicle. In this case, when the driver determines that there is no need to avoid the neighboring vehicle so that the driver tries to travel along the lane, an interference with the driver's operations is generated and the driver may experience discomfort.
On the other hand, in the technology disclosed in JP-A-2000-025631, the steering force is reduced according to the approach degree with respect to the inter-vehicle distance regardless of the lateral position of the preceding vehicle and the like. With such a configuration, since the control is reduced even when there is a sufficient lateral distance from the preceding vehicle, the driver cannot obtain an expected level of assistance.